In this experimental study four stroke, four cylinder, MPFI, SI engines were tested as per IS 14599. A group of six bifuel engines with different specifications was tested in gasoline mode and LPG mode. Engines were converted by using modification system to operate in LPG mode.
Objective of this experimental study was to compare performance and emissions of PFI passenger car engines in gasoline mode and LPG mode and to establish generic performance trend for LPG/Gasoline bifuel engines by defining and computing normalized figure of merit, power per unit displacement.
From experimental results, generic performance trend for passenger car engines was established. A unit parameter KW/lit was calculated for each engine for comparison in relation to rated torque, maximum exhaust gas temperature and speeds corresponding to maximum torque and maximum power. These graphs will be useful for engine designers to know general trend of gasoline and LPG PFI passenger car engines in the Indian auto market. Comparative emission study showed that CO, HC, Nox and CO2 emissions in LPG mode were reduced as compared to gasoline mode for both, urban and extra urban cycles.
Entire set of performance characteristics curves for one sample engine are plotted and are given in Appendix. Detailed analysis of results is presented in paper.